This invention relates to an arc suppression device which may be connected to existing power contactors substantially to eliminate arcing between the contacts thereof.
Semiconductor devices have been placed in parallel with the contacts of power contactors to reduce or suppress arcing during contact closure and opening, as shown in U.S. Pat. Nos. 3,260,894; 3,555,353; 3,639,808; 3,982,137 and 4,025,820.
In U.S. Pat. Nos. 3,260,894; 3,982,137 and 4,025,820, gating current to a semiconductor arc suppressing device is provided by an auxiliary contact connected mechanically to the movable contact of a power contactor. This auxiliary contact is designed to close prior to and open following the opening and closing of the power contacts so that the semiconductor device would be provided with gating current during that interval, but not while the main contacts were closed so that the semiconductor device would not be required to carry current continuously should the main contacts fail to close or close with an appreciable resistance therebetween.
U.S. Pat. No. 4,025,820 also discloses a protection current to prevent leakage current from flowing through the semiconductor device while the power contacts are open.
In all of the above devices, some modification or redesign of the power contactor or its associated control circuitry is necessary in order to incorporate the arc suppression means.
In copending U.S. application Ser. No. 7,947, filed Jan. 31, 1979, now U.S. Pat. No. 4,251,845, issued Feb. 17, 1981, assigned to the same assignee as the present invention, current is applied to the semiconductor devices before current is applied to or removed from the coil of the power contactor.